JPH0948209A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the weight of a tire and improve durability of a belt part by providing a plurality of air permeation preventing layers substantially covering the inner face of the tire, made of films of specific polymer composition, on a specific area. SOLUTION: A film 8 of polymer composition containing thermoplastic resin or blend of thermoplastic resin and elastomer of which air permeation coefficient is less than 25×10<-12> cc.cm/m<2> .sec≡mHg and Young's modulus is 1-500MPa, is arranged so as to substantially cover the whole tire inner circumferential face of a tire belt part. Next, because a plurality of layers of polymer film 8 as an air permeation preventing layer exist in the territories 9 including the belt end parts 10 of the belt width W and being over 25% of the belt width W in the widest belt part of a tire belt section, oxygen deterioration of the belt end parts 10 can be prevented. Further, because the gauge becomes very thin, air stagnation due to step difference is not generated, vulcanization trouble is not caused, and the weight can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire in which the weight of the tire is reduced and the durability of the belt portion is improved by partially forming an air permeation preventive layer.

[0002]

2. Description of the Related Art Reduction of the fuel consumption rate is one of the major technical problems in automobiles, and as a measure against this, there is an increasing demand for lighter pneumatic tires. By the way, an air permeation preventive layer such as an inner liner layer made of rubber having a low gas permeability such as halogenated butyl rubber is provided on the inner surface of the pneumatic tire in order to keep the tire air pressure constant.

Techniques have been proposed in which various materials are used as the inner liner layer of a pneumatic tire in place of low gas permeability rubber such as butyl rubber. For example,
-31761 discloses that the inner surface of a vulcanized tire has an air permeability coefficient [cm ³ (standard state) / cm · sec · mmHg] of 1 at 30 ° C.
It is disclosed that a solution or dispersion of synthetic resin such as polyvinylidene chloride, saturated polyester resin, polyamide resin or the like having a concentration of 0 × 10 ⁻¹³ or less and 50 × 10 ⁻¹³ or less at 70 ° C. is applied in an amount of 0.1 mm or less. There is.

JP-A-5-330307 discloses that the inner surface of a tire is subjected to a halogenation treatment (using a conventionally known chlorination treatment solution, a bromine solution, an iodine solution), and a methoxymethylated nylon Polymer film of polymerized nylon, blend of polyurethane and polyvinylidene chloride, blend of polyurethane and polyvinylidene fluoride (film thickness 1
0-200 [mu] m).

Further, Japanese Patent Laid-Open No. 5-318618 discloses that
A pneumatic tire using a thin film of methoxymethylated nylon as an inner liner is disclosed. According to this technology, a solution or emulsion of methoxymethylated nylon is sprayed or applied to the inner surface of a green tire, and then the tire is vulcanized. Alternatively, a pneumatic tire is manufactured by spraying or applying a solution or emulsion of methoxymethylated nylon on the inner surface of the tire after vulcanization.

Further, Japanese Patent Laid-Open No. 6-40207 discloses that
A non-air permeable layer composed of a polyvinylidene chloride film or an ethylene vinyl alcohol copolymer film, and a polyolefin film, an aliphatic polyamide film, or a multilayer film having an adhesive layer composed of a polyurethane film as an air permeation preventive layer of a tire. There is an example in use.

[0007]

As described above, various materials for the inner liner layer of a pneumatic tire have been proposed in place of butyl rubber, but have not yet been put to practical use. Under such circumstances, we have previously found that a new air permeation preventive layer material containing a thermoplastic resin or a blend of a thermoplastic resin and an elastomer has an air permeation coefficient of 25 × 10 ⁻¹² cc · cm / cm. ²・ sec ・ cmHg
A polymer composition for a tire having a Young's modulus of 1 to 500 MPa was proposed below (for example, Japanese Patent Application Nos. 7-150353, 7-28318, 7-28257 and 7-268).
No. 44, No. 7-28320, No. 7-11752, etc.).

By the way, when the air permeation preventive layer is applied to the tire belt portion, as shown in FIG. 1, in the case of the conventional butyl rubber liner, it is not possible to change the shape of the butyl rubber liner from the first molding step to the second molding step during processing. The gauge shown in 1 below makes the gauge under the belt thinner, so in anticipation of this,
Originally, a thick uniform gauge was used for processing (in FIG. 1, 1 indicates a molding drum, and 2 indicates an air permeation preventive layer).
Therefore, if the gauge at the lower part of the belt is sufficiently secured, there is a problem that the liner gauge becomes thicker than necessary at the bead portion and the side portion where the lift amount is small, and the tire mass increases. Therefore, it has been proposed to extrude a portion having a large lift amount thickly (see Japanese Patent Application Laid-Open No. 4-77243), and it is conceivable to make a portion having a large lift amount multi-layered. However, in the case of the former, there is a problem that there is a limit to weight reduction because a low gas permeable rubber is used for the inner liner layer, and in the case of the latter, if the gauge per layer is thick, it will be due to the multilayer structure. There is a problem that a new step occurs, especially a problem of air accumulation, and if the gauge per contact is thinner, the modulus of the green rubber is low, so that the moldability of handling the rubber sheet is deteriorated.

The problem of air accumulation is, for example, as shown in FIG. 2, when a belt layer, a carcass layer 5 and partially two layers of butyl rubber air permeation preventive layer 6 are provided under a tire tread 3, butyl rubber is used. The layer has a thick gauge, and as a result, an air pool 7 as shown in FIG. 2 is inevitably formed at the end of the air permeation preventive layer of the second layer, which causes a vulcanization failure. Therefore, it is an object of the present invention to provide a pneumatic tire which eliminates the above-mentioned problems of the prior art and which is excellent in weight saving of the tire and improvement in durability of the belt portion.

[0010]

According to the present invention, a thermoplastic resin having an air permeability coefficient of 25 × 10 ⁻¹² cc · cm / cm ² · sec · cmHg or less and a Young's modulus of 1 to 500 MPa or a thermoplastic resin. A film of a polymer composition containing a blend of an elastomer and an elastomer, having an air permeation preventive layer that substantially covers the inner surface of the tire, the air permeation preventive layer being the widest tire belt part, at least the belt end part Provided is a pneumatic tire including and including a plurality of layers from each belt end to an area of 25% or more of the belt end.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the structure, operation and effect of the present invention will be described in detail. Film forming the air permeation preventive layer of a pneumatic tire according to the present invention, air permeability ^{25 × 10 -12 cc · cm /} cm 2 · sec · cmHg or less, - preferably 5 × 10 ^{-1 2} cc cm / cm ² · sec · cmHg and Young's modulus is 1 to 500 MPa, preferably 10 to 300 MPa
And the thickness of the film is preferably 0.02 to
0.2 mm, more preferably 0.05 to 0.2 mm.
Air permeability is 25 × 10 ^-12 cc · cm / cm ² · sec · cmHg
Exceeding this is not preferable in terms of reducing the weight of the pneumatic tire. On the other hand, if the Young's modulus is too low, wrinkles or the like occur during the molding of the tire, which lowers the molding processability.

The thermoplastic resin may be any material having an air permeation preventive action. Examples of such a thermoplastic resin include the following thermoplastic resins and any polymer mixtures of these or these and elastomers.

Polyamide resin (for example, nylon 6 (N
6), nylon 66 (N66), nylon 46 (N4
6), nylon 11 (N11), nylon 12 (N1
2), nylon 610 (N610), nylon 612
(N612), nylon 6/66 copolymer (N6 / 6
6), nylon 6/66/610 copolymer (N6 / 66
/ 610), nylon MXD6 (MXD6), nylon 6T, nylon 6 / 6T copolymer, nylon 66 / PP
Copolymer, nylon 66 / PPS copolymer), and N-alkoxyalkylated products thereof, for example, 6-nylon methoxymethylated product, 6-610-nylon methoxymethylated product, 612-nylon methoxymethylated product, polyester Resin (eg polybutylene terephthalate (PBT), polyethylene terephthalate (PE
T), polyethylene isophthalate (PEI), PET
/ PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester, aromatic polyester such as polyoxyalkylenediimidic acid / polybutyrate terephthalate copolymer), polynitrile resin (eg polyacrylonitrile) (PA
N), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), methacrylonitrile / styrene copolymer, methacrylonitrile / styrene / butadiene copolymer), polymethacrylate resin (for example, polymethylmethacrylate ( PMMA), polyethylmethacrylate), polyvinyl resins (eg vinyl acetate, polyvinyl alcohol (PVA), vinyl alcohol / ethylene copolymer (EVOH), polyvinylidene chloride (PDV)
C), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, vinylidene chloride / methyl acrylate copolymer, vinylidene chloride / acrylonitrile copolymer), cellulosic resins (eg cellulose acetate, cellulose acetate butyrate), Fluorine-based resin (for example, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF),
Examples thereof include polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer), and imide resin (for example, aromatic polyimide (PI)).

The elastomer that can be blended with the thermoplastic resin is not particularly limited as long as it has the above-mentioned air permeability coefficient and Young's modulus as a blend, and examples thereof include the following. Diene rubber and its hydrogenated products (for example, NR, IR,
Epoxidized natural rubber, SBR, BR (high cis BR and low cis BR), NBR, hydrogenated NBR, hydrogenated SBR),
Olefin rubber (for example, ethylene propylene rubber (E
PDM, EPM), maleic acid modified ethylene propylene rubber (M-EPM), IIR, isobutylene and aromatic vinyl or diene monomer copolymer, acrylic rubber (A
CM), ionomers), halogen-containing rubbers (eg Br
-IIR, Cl-IIR, bromide of isobutylene paramethylstyrene copolymer (Br-IPMS), CR, hydrin rubber (CHR), chlorosulfonated polyethylene (CSM), chlorinated polyethylene (CM), maleic acid modified chlorinated Polyethylene (M-CM)), silicone rubber (for example, methyl vinyl silicone rubber, dimethyl silicone rubber, methylphenyl vinyl silicone rubber), sulfur-containing rubber (for example, polysulfide rubber), fluororubber (for example, vinylidene fluoride rubber, fluorine-containing vinyl ether rubber) Rubber, tetrafluoroethylene-propylene rubber, fluorine-containing silicon rubber, fluorine-containing phosphazene rubber, thermoplastic elastomer (for example, styrene elastomer, olefin elastomer, ester elastomer, ureta) System elastomer, polyamide-based elastomer) and the like.

When the compatibility between the specific thermoplastic resin and the elastomer component is different, it is preferable to use a suitable compatibilizing agent as the third component to make them compatible.
By mixing the compatibilizer into the system, the interfacial tension between the thermoplastic resin and the elastomer component is reduced, and as a result, the rubber particles forming the dispersion layer become finer, so that the properties of both components are more improved. It will be effectively expressed. Such a compatibilizer is generally a copolymer having a structure of both or one of a thermoplastic resin and an elastomer component, or an epoxy group, a carbonyl group, a halogen group, an amino group capable of reacting with the thermoplastic resin or the elastomer component. It can be a copolymer having a group, an oxazoline group, a hydroxyl group and the like. These may be selected according to the type of thermoplastic resin and elastomer component to be mixed,
Commonly used ones are styrene / ethylene / butylene block copolymer (SEBS) and its maleic acid-modified product, EPDM, EPDM / styrene or EPDM / acrylonitrile graft copolymer and its maleic acid-modified product, styrene / maleic acid Copolymers, reactive phenoxines and the like can be mentioned. The amount of the compatibilizer is not particularly limited, but is preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the polymer component (total of the thermoplastic resin and the elastomer component).

When the thermoplastic resin and the elastomer are blended, the composition ratio of the specific thermoplastic resin (A) and the elastomer component (B) is not particularly limited, and the film thickness, the air permeation resistance, the flexibility The weight ratio (A) / (B) is preferably 10/9, although it may be appropriately determined depending on the balance of properties.
0-90 / 10, more preferably 20 / 80-85 / 1
5

In addition to the above-mentioned essential polymer components, the polymer composition according to the present invention is mixed with other polymers such as the above-mentioned compatibilizer polymer within a range that does not impair the required properties of the tire polymer composition of the present invention. can do. The purpose of mixing other polymers is to improve the compatibility between the thermoplastic resin and the elastomer component, to improve the film moldability of the material, to improve the heat resistance, to reduce the cost, etc. Examples of the material used include polyethylene (PE), polypropylene (PP),
Examples thereof include polystyrene (PS), ABS, SBS, SEBS, polycarbonate (PC) and the like. Further, olefin copolymers such as polyethylene and polypropylene, maleic acid-modified products thereof, and glycidyl group-introduced products thereof can also be mentioned. The polymer composition according to the present invention further comprises a filler which is generally blended in the polymer blend,
Carbon, quartz powder, calcium carbonate, alumina, titanium oxide and the like may be optionally added as long as the requirements for the air permeability coefficient and Young's modulus are not impaired.

According to the present invention, as shown in FIGS. 3 and 4, the air permeability coefficient is 25 × 10 ⁻¹² cc · cm / cm ² · sec.
A film 8 of a polymer composition containing a thermoplastic resin or a blend of a thermoplastic resin and an elastomer having a Young's modulus of 1 to 500 MPa and a cmHg or less is arranged so as to substantially cover the entire inner circumferential surface of the tire belt portion. The method of arranging the polymer film 8 is not particularly limited and may be considered infinitely large. However, as illustrated in, for example, FIGS. 3-1 to 3-7, at least one layer of polymer is formed on substantially the entire tire inner peripheral surface. There is a film, and there is at least partially a two or more layer polymer film. The materials of the two or more polymer films may be the same or different. Further, the polymer film may be attached or adhered after molding according to a conventional method, or may be applied according to a conventional method. Further, the plurality of films need not be adjacent to each other as long as they are inside the belt, and for example, a carcass layer may be present between them.

Next, according to the present invention, as shown in FIG. 4, in the widest belt portion of the cross section of the tire belt portion, the belt end portion 10 having the belt width W is included and the belt ends 10 to 10 In order to prevent oxygen deterioration at the belt end, it is necessary that a plurality of polymer films 8 serving as air permeation preventive layers are present in the region 9 of 25% or more of the width W.

Further, in a preferred embodiment of the present invention, FIG.
The relationship between the step amount S (mm) and the thickness t (mm) per layer of the film liner shown in (a) is preferably 25t ≦ S in order to prevent air accumulation due to a step.
As shown in FIG. 5 (b), when the step amount S is small, the thickness of each layer of the polymer films 8, 8 ', 8 "is thin, but the overall step is large, which causes a vulcanization failure due to air accumulation. However, when the upper polymer film 8'covers the lower polymer film 8 "as shown in FIG. Does not happen.

[0021]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but it goes without saying that the technical scope of the present invention is not limited to these Examples. Examples 1-6 and Comparative Examples 1-7 As shown in Table I, tires (size: 165SR13, rim size: 13) having an air permeation preventive layer configured as shown in Table I using polymer films made of materials A to D are used. × 4
1 / 2-J) was prepared. The following tests were conducted on these tires and conventional standard examples. The results are shown in Table I.

Air dripping test method The tire after vulcanization was cut, and if air dripping failure was observed, it was judged as bad (x), and if not observed, it was judged as good (◯).

Test Method for Molding Workability During tire molding, if the material was stretched, it was rated as bad (x), and if it was not stretched, it was rated as good (◯).

Belt Durability Test Method Under the dry heat deterioration conditions and the following running conditions, a failure (x) is given when a failure such as separation occurs in the belt, and a good one (◯) when no failure occurs. (1) Dry heat deterioration condition: Oxygen is sealed in the tire at a pressure of 350 kPa and deteriorated at a temperature of 70 ° C. for 14 days. (2) Driving conditions: 1 on the standard rim specified by JATMA
Air was enclosed at a pressure of 70 kPa, a camber angle of -2 ° was given on a drum of 1707 mm, and a speed of 60 km / h was applied for 10 minutes.
Run for 0 hours. The load is 75 ± 24% of the maximum load capacity specified by JATMA with a sine wave of 0.03 Hz,
At the same time, a slip angle of ± 3 ° is given by a corrugated pattern whose phase is shifted by 180 °.

Air leak test method (pressure drop rate) Initial pressure of 200 kPa, room temperature of 21 ° C., and no load for 3 months. The internal pressure measurement interval is every 4 days, and the measured pressure is
As Pt, initial pressure Po, and elapsed days t, the α value is obtained by regressing to the following equation Pt / Po = exp (−αt). Using the obtained α, t = 30
Substituting (day), β = [1-exp (−αt)] × 100 is obtained. This value β is the pressure drop rate per month (% /
Month).

[0026]

[Table 1]

[0027]

[Table 2]

Table I Footnotes (All parts indicate parts by weight) Material A: Nylon 6 (N6) (Toray CM4061)
28 parts, nylon MXD6 (MXD6) (Mitsubishi Gas Chemical Reny 6002) 42 parts, maleic acid modified ethylene propylene rubber (M-EPM) 30 parts and methylene dianiline 0.18 parts, having an air permeability coefficient of 2.13. × 1
^0-12 cc · cm / cm ² · s. cmHg) Young's modulus is 257 MPa
Material. Material B: N6 25.2 parts, MXD6 37.8 parts, Masterbatch A (butyl rubber bromide: Exxon Chemical Exxon Bromobutyl 2244 100 parts, Tokai Carbon Carbon Black GPF: Seast V 60
Part, stearic acid 1 part, petroleum-based hydrocarbon resin Essolets 1102 10 parts, paraffin-based process oil 10 parts) 48.9 parts, Mitsui Petrochemical high sex million 240M (EEA), zinc oxide 1.5 parts, DM0.
It consists of 5 parts and 0.3 parts of sulfur and has an air permeability coefficient of 0.
84 × 10 ^-12 cc · cm / cm ² · sec. Material with cmHg and Young's modulus of 244 MPa Material C: N6 25.2 parts, MXD6 37.8 parts, B
It consists of 27.0 parts of r- (polyisobutylene-p-methylstyrene) (EXPRO 89-4 manufactured by Exxon Chemical) and nylon 6 / nylon 66 / nylon 610 (CM4001 manufactured by Toray), and has an air permeability coefficient of 0.63 ×.
10 ^-12 cc · cm / cm ² · sec. cmHg Young's modulus 317MP
Material of a Material D: Butyl rubber (Air permeability coefficient 55 × 10 ^-12 cc ・
cm / cm ² · sec. cmHg, Young's modulus 15MPa)

[0029]

As described above, according to the present invention,
Air permeability coefficient is 25 × 10 ^-12 cc · cm / cm ² · sec. cm
A preferable 0.02-0.2 mm thick film of a polymer composition containing a thermoplastic resin having a Young's modulus of 1 to 500 MPa or less and a blend of a thermoplastic resin and an elastomer is used as an air permeation preventive layer. By providing multiple layers of the prevention layer in a specific area, 1) the gauge becomes extremely thin, so air gaps do not occur at the steps unlike in the past, and it does not cause vulcanization failure. 2) Even if the gauge is thin ,
Moldability is not deteriorated due to high modulus, and 3) gauge is thin, which enables weight reduction, and 4)
Since the amount of air (oxygen) passing through the belt portion is reduced, the oxygen deterioration of the belt coat rubber is reduced, and the tire durability is improved.

[Brief description of drawings]

FIG. 1 is a view for explaining a problem that occurs in an air permeation preventive layer below a belt during a conventional tire molding process.

FIG. 2 is a diagram illustrating a problem of air accumulation when the air permeation preventive layer below the belt is increased in quantity.

FIG. 3 is a drawing showing the arrangement of a polymer film of an air permeation preventive layer according to the present invention in a cross section of a tire belt portion, and some embodiments thereof are shown in FIGS. (3-1) to (1-6).

FIG. 4 is a drawing showing an example of requirements for the arrangement of a plurality of layers in a tire belt section of the polymer film of the air permeation preventive layer according to the present invention.

FIG. 5: Step amount S in a preferred embodiment of the present invention
FIG. 5 is a drawing showing the relationship between (mm) and the thickness (mm) per one layer of the air permeation preventive layer, and FIG. 5 (a) is a drawing showing the arrangement when the partial polymer film has two layers. 5 (b)
Is a drawing showing that even if the step amount is small and the thickness per layer is thin, the whole step becomes large, which causes vulcanization failure due to air accumulation, and FIG. 5 (c) shows the upper polymer film. 8'is the lower polymer film 8 "
Is a drawing showing that even if the step amount S is small, air accumulation does not occur.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Molding drum 2 ... Air permeation prevention layer 3 ... Tire tread 4 ... Belt layer 5 ... Carcass layer 6 ... Air permeation prevention layer (2 layers) 7 ... Air pool 8,8 ', 8 "... Polymer film 9 ... Plural Area for arranging the air permeation preventive layer 10 ... Edge of the widest belt portion

Claims (2)

[Claims] 1. An air permeability coefficient of 25 × 10 ⁻¹² cc · cm /
cm ² · sec · cmHg or less and Young's modulus of 1 to 500 MPa, which is made of a film of a polymer composition containing a thermoplastic resin or a blend of a thermoplastic resin and an elastomer, and has an air permeation preventive layer that substantially covers the inner surface of the tire. In the tire belt portion having the widest width, the air permeation preventive layer includes at least the belt end portions, and a plurality of layers are arranged in an area of 25% or more of the belt width from each belt end. 2. The thickness of one air permeation preventive layer is 0.02.
The pneumatic tire according to claim 1, which has a diameter of about 0.2 mm.